The Jaz, now known as Jaz-O (real name: Johnathan Burks) is an East Coast MC, active in the late 1980s and early 1990s, best known for being a mentor of sorts to Jay-Z. Jaz is also known as the Originator and had a song called "The Originators" that featured a young Jay-Z in 1989. As simply the Jaz, he had success with his 1990 single "Hawaiian Sophie," from his debut album Word to the Jaz. He has been featured on some of Jay-Z's songs, such as "Bring it On" (from Reasonable Doubt) and the single "Nigga What, Nigga Who (Originator 99)" (from Vol. 2: Hard Knock Life) as Big Jaz and produced the single "Ain't No Nigga" from Reasonable Doubt and the song "Rap Game/Crack Game" from In My Lifetime, Vol. 1. Jaz-O is known to have discovered Jay-Z. Jaz-O claims that Jay-Z got his name from Jaz, something Jay-Z denies. Jaz badmouthed Jay-Z in a couple of interviews.

Jaz was an important figure in the Nas vs. Jay-Z feud. It is also speculated that Jaz-O supplied Nas with some of the information he used in his Jay-Z diss track "Ether." After the situation with Nas cooled down, Jay-Z went on to diss Jaz first on a track released by DJ Kay Slay featuring Freeway, Geda K, Young Chris, and Memphis Bleek and later on his album The Blueprint 2: The Gift & The Curse. Jay-Z said on the title track, "I'ma let karma catch up to Jaz-O." Jaz responded with a record on a DJ Kay Slay mixtape called "It's Ova."